This last part unleashed, if not a tidal wave, then at least a bracing, frothy surf of Twitter smugness. Didn't Activision know that the Roman numerals for four is IV? It's not Star Wars: Episode IIII is it? Ice-T didn't call one of his albums IIII. (Okay, so I have just googled this and he didn't call it IV, either. He called it VI. Full name: Ice-T VI: Return of the Real. It's a banger. Also, nobody mentioned Ice-T on Twitter - I simply needed a second flippant example to make this paragraph work and I chose poorly.)

Jeez! Some fans apparently leapt into action by suggesting that the IIII does in fact represent tally marks, of the kind you are required to scratch onto the wall of your cell if you are a prisoner in a montage constructed to show the passage of time. The thing is, though, those IIIIs on Call of Duty don't look like tally marks. They don't really look like very much beyond the cow-catcher on an old steam train - but they at least sort of look like Roman numerals.

So. IIII or IV? Which should it be? The internet couldn't decide. I have read arguments for both sides before I got bored and went off to do something else. Some people think that IV is the only option. Some people state that IIII is also acceptable - and possibly more accurate in fact. Some people prefer IIII because it is just so novel. Some people wanted World War 2 again anyway. No matter. These are disputatious days we are living through, and I was intrigued. I sensed the potential to get to the bottom of this, to pierce the veil of a great mystery that had somehow survived the ages intact.

I also sensed that I had a killer excuse to call a special phone number that puts you through to a room deep in the British Museum where, if you speak the hallowed words, "Can I talk to the duty curator?" a brilliant academic will come to the phone and then has to try and find out the answer to your stupid question. (I should add that I only know about this phone number because of a fantastic lady I used to chat to while dropping my daughter off at nursery in Rottingdean.) Anyway, I dialled Greece and Rome. I requested the duty curator. Then, I asked him: What is it, IIII or IV? And he said he would get back to me.

And he did. And get this: IIII and IV are both legit, by the looks of it. Romans did apparently use both, and sometimes they even used both in the course of a single document. (I almost ended that sentence with an exclamation mark, such is the scandalous frisson of merely typing such a thought.)

Also, if you are boring like me, this stuff is actually quite interesting. Roman numerals are created by addition, subtraction and multiplication, I have been told by the British Museum duty curator for Greece and Rome. Often addition (IIII = 4) was preferred to subtraction (IV = 4). The subtraction notation - also called the subtractive notation, which is moderately cooler to say but I'll admit it's a squeaker - was not used exclusively until the 13th century, in fact - and it was not universally adopted in the Roman period. ('Exclusively' is not quite right either, of course - modern watchmakers in particular remain fond of IIII.)

And get this, everyone: reading around, I discovered that it has been argued that the subtraction notation was developed after the addition notation, and you can kind of glimpse the reasoning behind this for yourself if you think of the subtraction notation as being, well, a form of shorthand. IV could have followed on from IIII quite naturally because it required fewer characters and was less effort. (You can see this most clearly if you compare 9s: VIIII is a bit of an awkward pain that nobody wants to get stuck in an elevator with; IX is rather dashing.)

Bonus fact, because it is Friday: M was never used by the Romans to represent 1000 and only became popular in the 15th century in England. Blammo!

Thanks curator, who I suspect from his email did not particularly wish to be named in a report of this quality. He did want me to cite the following sources, however, one of which I have since purchased on Amazon because I guess this is who I am now:

Also, he did remind me that he is not a Latin epigrapher. On this we find common ground.

So anyway: IIII is fine, I guess. IV would also be fine. Everyone can stop worrying!

(And yes, your big takeaway from this piece should really be that you can call the British Museum if you ever have a query about something related to the museum's collections and they will try to answer it for you. This is such an amazing thing to learn that I could just float with happiness.)